This invention relates to compositions which contain polycarbonate and an aliphatic thio compound: and, in particular, it relates to articles which, when molded from such compositions, do not exhibit surface defects upon release from a mold.
Polycarbonate has found many uses because, in general, it combines a high level of impact resistance, tensile strength, heat resistance and dimensional stability. However, in some instances in which it is being injection molded at high speeds, the article being molded suffers from a tendency to fail to cleanly release from a mold upon the completion of molding. Such unwanted adhesion, or "sticking", to a mold frequently leaves a molded article with noticeable surface defects, herein sometimes called "stick marks". Accordingly, it would be desirable to protect articles molded from polycarbonate from the occurrence of such surface defects by forming such articles from a polycarbonate composition prepared by admixing polycarbonate with a substance which promotes clean release from a mold with no adhesion thereto. It would be particularly desirable to utilize, in the formation of such a composition, a substance which not only does not cause an offsetting decrease in other properties of polycarbonate, but preferably improves those properties.
In 66 Modern Plastics at page 122 (January 1989), the use of Anoxsyn.TM. 442 bis alkyl sulfide as an antioxidant for olefin polymers is described. However, no mention is made therein of using Anoxsyn.TM. 442 bis alkyl sulfide in conjunction with polycarbonates, no mention is made of using Anoxsyn.TM. 442 bis alkyl sulfide for the purpose of overcoming the problem of the unwanted adhesion of a molded article to a mold, and the detailed chemical composition of the substance being sold at that time under that trade name is not set forth.